When an electrically controlled shutter or an automatic diaphragm, wherein light measuring is performed with a photosensitive element disposed in the path of light entering the photographic optical system, is incorporated into a through-the-lens type, single lens, reflex camera, there occurs a disturbance in the internal resistance of the photosensitive element due to the springing up of the quick return mirror. To overcome such a problem, there has already been proposed a means to store the information converted from the intensity of light reflected from an object to be photographed and then to control the shutter operation in accordance with the stored information. In such means a capacitor storage device has been utilized to store the intensity information but such a storage means is disadvantageous because the longer the shutter time is, the more serious the influence of capacitor leak current upon the information stored and the larger the capacity of the storing capacitor must be. This results in a longer time required for both charge and discharge of the capacitor and a more serious problem arising from the chattering of the switch connected to the discharge circuit for the capacitor.